Knife and scissors sharpener improvements



July 5, 1966 K. R. CLARK 3,253,873

KNIFE AND SCISSORS SHARPENER IMPROVEMENTS Filed 001:. 31, 1963 2 Sheets-Sheet 1 INVENTOR" a Jew e zawA July 5, 1966 K. R. CLARK KNIFE AND SCISSORS SHARPENER IMPROVEMENTS Filed on. 51. 1963 2 Sheets-Sheet 2 INVENTOR BY W 26% Q United States Patent 3,258,878 KNIFE AND SCISSORS SHARPENER IMPROVEMENTS Kenneth R. Clark, Wauwatosa, Wis, assignor to John Oster Manufacturing Co., Milwaukee, Wis, a corporation of Wisconsin Filed Oct. 31, 1963, Ser. No. 320,282 3 Claims. (Cl. 51-80) This invention relates to a household knife and scissors sharpener of the type utilizing two motor driven abrasive wheels, and more particularly, to improvements in a household knife and scissors sharpener of the type shown in Madl et a1. Pat. No. 2,865,141, assigned to the same assignee as the instant application.

Combined knife and scissors sharpeners following the teachings of the Madl patent have been manufactured and sold by the assignee of the present invention with considerable commercial success. They provide a unitary apparatus which will not only hollow grind knife blades presented in the knife sharpening groove but will also proficiently sharpen scissors blades in a separate groove formed in the housing which has an inclined guide surface. However, some people using this product have been lacking in skill to properly utilize the scissors sharpening feature. Sometimes the user would not maintain the scissors blade firmly in contact with the inclined scissors guide surface against the rotational force of the sharpening wheel. This resulted in chatter marks along the shearing edge of the scissors blade. Further, with the abrasive wheels arranged as disclosed in the Madl patent, the scissors blade could not be sharpened close to the pivotal connection or crotch of the scissors. It would be desirable, therefore, to have a combined knife and scissors sharpener which would retain the advantages of the Madl sharpener and yet overcome the disadvantages noted above.

It is an object of the present invention to provide a combined knife and scissors sharpening apparatus which is easily used by the unskilled.

It is a further object of the present invention to provide an apparatus for sharpening both knives and scissors having a scissors guide surface which is positioned so that the rotation of the abrasive wheel tends to maintain the scissors shearing blade against the scissors guide surface.

Another object of the present invention is to provide a motor operated, two abrasive wheel household apparatus for sharpening knives in a hollow ground manner and also sharpening scissors blades at the correct angle close to the crotch thereof while providing support for said scissors blade throughout the sharpening operation.

Further objects and advantages of the present invention will become apparent as the following description proceeds and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

Briefly, in the preferred embodiment of the present invention, two overlapping abrasive wheels are disposed on spaced parallel axes within a housing having a top and front wall. When viewed from the front, Where blades are presented for sharpening, the left abrasive wheel is closer to the front wall. Two spaced parallel grooves are formed in the housing across the top and through to the front wall. The knife grove on the right side is perpendicular to the front wall and overlies the intersection of the two wheels. The other groove for scissors passes over the left front wheel and has a vertical scissors glide surface which is offset from the wheel axes in a direction remote from the other wheel. Both grooves terminate in openings exposing the sharpening face of the abrasive wheels which rotate in opposite directions. Both wheels ice rotate upwardly toward the line of intersection therebetween.

For a better understanding of the present invention, a preferred embodiment thereof will be described by reference to the accompanying drawings in which:

FIGURE 1 is a front perspective view of a combined knife and scissors sharpener embodying the present invention;

FIG. 2 is a sectional view taken along the section line 22 of FIG. 3 showing a scissors blade in the sharpening position;

FIG. 3 is a "broken away top plan view of the device;

FIG. 4 is a sectional View taken along the section line 4--4 of FIG. 3; and

FIG. 5 is an enlarged view of the left-hand groove and wheel of FIG. 4 with the scissors blade in sharpening position.

Referring now particularly to the accompanying drawings, illustrated therein is an electric knife and scissors sharpening apparatus indicated generally by reference numeral 10. The device comprises an elongated cup shaped housing 11 which encloses a pair of rotatably mounted abrasive wheels 12 and 13 of substantially equal diameter. The wheels are driven by an electric motor 14 mounted on a cast T-shaped frame 15.

In order to better understand the function of this invention, it is well to identify the standard parts of a typical scissors 20. As illustrated in FIGS. 2 and 5, the scissors 20 comprises identical shearing blades 21 and 22 which are pivotally fastened together by a screw 23. The inside surface 24 of each blade is substantially flat and terminates at a cutting edge 25 formed by the intersection of a land 26 with flat surface 24. The lands 26 are accurately sharpened to the proper angle for correct shearing action as can be seen in FIG. '5, and both blades have conventional not shown handle portions to facilitate their use.

The mechanism inside the housing 11 comprising the motor 14 and a power transmission arrangement may be like that shown in Fillweber Pat. No. 2,707,852, also assigned to the assignee of the instant invention. As may be seen in FIG. 3, the electric motor 14 is fastened to an upright portion 16 of frame 15 by a plurality of threaded members 17, only one of which is illustrated. The horizontally mounted armature shaft 18 has a fan member 19 positioned at one of its ends and shaft 18 is supported for rotation by integrally cast in-line bearing portions 30 and 31 of frame 15. When viewed from FIG. 2, shaft 18 rotates in a clockwise direction. Disposed on shaft 18 and between the supporting bearing portions 30 and 31 is a tubular power transmission member 35. Member 35 is rigidly attached to shaft 18 by a pin 36. Preferably, the transmission member 35 is molded of plastic material with integral worm gear teeth 37 and 38 of opposite thread. That is to say, Worm 37 has a right-hand thread while worm 38 has a left-hand thread.

As may be seen in FIG. 3, frame 15 has parallel bearing portions 39 and 40 formed at a right angle to the inline bearings 30 and 31. Received within bearing 39 is spindle 41 having gear 42 positioned at one end which is engaged with worm teeth 37. Carried at the other end of spindle 41 is a relatively thin cylindrical abrasive wheel 12 which is hereinafter referred to a the first or left wheel. The first wheel 12 has a sharpening periphery or face 46 and rotates about its horizontal axis 43. Retaining the first wheel 12 in position is clip 47 which locks onto spindle 41. Similarly, bearing 40 receives spindle 50 which has mounted at one end thereof gear 51 in engagement with worm 3S and grinding wheel 13 hereinafter referred to as the second or right wheel disposed at the other end. The second wheel 13 has a peripheral cutting surface or face 44 and is retained on spindle 50 by means of a clip 55. Located between wheel 12 and bearing 39 is a tubular spacer 56 which positions first or left wheel 12 slightly ahead of second or right wheel 13 as is seen in FIG. 3. Wheel 13 rotates about its axis 57 which is parallel to the first wheel axis 43 and sufliciently close thereto so that the peripheries of 'wheels 12 and 13 overlap as seen in FIGS. 4 and to form an upper line of intersection which is indicated as reference numeral 60. Power transmission member rotates wheels 12 and 13 in opposite upward directions and toward the line of intersection 60. The line of intersect-ion 60 defines the lower end of a vertical sharpening plane for knives, and it is necessary that the wheels rotate against the knife edge to be sharpened in order to prevent the kife edge from being drawn into the wheels.

Closing the bottom of cup-shaped housing 11 is an L-shaped support plate 62 which is adapted to receive frame 15 by means of not shown threaded members. Depending from the bottom of the support plate 62 are a plurality of supporting feet 63 which are preferably fabricated from rubber to minimize vibrations from operation of the appliance. The feet 63 are secured to the plate by not shown threaded members. The upright portion 61 of the L-shapcd support plate 62 cooperates with the end of the housing 11 to form a cord storage chamber 65 for a power cord 64 which conveys electrical energy to the motor 14.

The housing 11 which encloses the grinding mechanism comprises a top Wall 70, front wall '71, rear wall 72, right side 73 and left side 74. The grinding wheels 12 and 13 are positioned adjacent the front wall 71. Super-imposed over the top of the housing 79 is a slid-able cover 75 which is utilized to shield the grinding wheels when the apparatus is not in use and also to actuate an electrical control switch 76 That is to say, when the cover 75 is moved to the closed position covering the grinding wheels, the switch '76 is opened by a not shown tab depending from the cover, and when the never is moved to the position shown in FIGS. 1 and 4, a tab 77 depending from the cover closes the switch. integrally formed with the housing 11 are knife groove 78 and scissors groove 79. They are disposed in spaced parallel relationship with each other and extend downwardly from the top wall 70. When viewed from the front, which is the direction from which knives or scissors must be presented for sharpening, the scissors groove 79 is positioned to the left of the knife groove 73, as seen in FIG. 4. The knife greoye 78 is formed by de ending Walls 81 and 82 I Groove 78 terminate at its lower end at knife opening 80. Opening is positioned over the line of intersection 60 to partly expose grinding wheels 12 and 13. Thus, when a knife blade is inserted into "groove 78, it will contact the grinding wheels for sharpening the blade with a hollow ground edge as is well known in the art.

Overlying first wheel 12 i scissors sharpening groove 79. Groove 79 is formed by an inclined wall 85 and a vertical wall 87 depending from the top wall 70. Groove 79 terminates at scissors opening 86. The inside vertical surface 88 of wall 87 provides an accurate guide surface for scissors blades to be positioned against during the sharpening operation, and extends completely across wheel face 46 to afford control thorughout the sharpening operation. To assure that the proper angle is ground on the scissors blade, the vertical guide surface '83 is offset from the first wheel axis in a direction remote from the second wheel axis. Thus, as can be seen in FIG. 5, the correct shearing angle on the scissors blade land 26 will be ground by the first abrasive wheel face 46. The land 26 is ground along a line designated by reference numeral 89 to illustrate the sharpening angle on the scissors blade 22. Moreover, it will be appreciated that the rotation of first wheel 12 i in such a direction as to maintain the scissors blade against the guide surface 88. Therefore, it is not necessary for the operator to maintain the scissors blade firmly against the guide surface 83. Rather, the sharpening action of the wheel will do this.

As illustarted in FIG. 2, the housing 11 has a ledge 90 in front of scissors groove 79 and knife groove 78, which forms a recessed portion 71a of front wall 71. The scissors blade 21 not being sharpened tends to limit the travel of the scissors blade 22 being sharpened into the apparatus since blade 21 abuts front wall 71. With the present invention, the blade 21 can be inserted into the apparatus to sharpen it well into the pivotal connection or crotch area of the scissors. This is because the scissors sharpening wheel 12 is positioned in front of the other wheel 13 and adjacent to the recessed portion 71a of the front wall 71.

While there has been illustrated and described a particular embodiment of the invention it will be understood that changes and modifications may occur to those skilled in the art and it is therefore contemplated by the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the present invention.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. In an electrically operated apparatus for sharpening scissors of the type having two shearing blades which are pivotally connected [together and knives including a first and second abrasive wheel positioned on parallel horizontal axes which are located sufficiently close together so that the peripheries of said wheels overlap slightly and said first wheel is slightly in front of said second wheel, .a housing including a top wall superimposed over said wheels and a front wall facing the side from which knives and scissors are presented for sharpening, said first wheel being positioned to .the left of said second wheel from the front and having an abrasive face on the periphery, the overlapping of said twheels defining an upper line of intersection, electrical means for rotating said wheels in opposite direction whereby both wheels rotate upwardly at the line of intersection, said top wall having a knife groove adapted for receiving knives to be sharpened which is parallel to and positioned over said line of intersection and defines a knife opening exposing said intersection, a scissors groove formed in said top wall parallel to and spaced to the left of said knife groove, said scissors groove being formed in part by a straight flat guide surface which lies in a substantially vertical plane, said surface extending completely acros the face of said first wheel and offset from said first wheel axis in a direction away from said second wheel axis whereby tthe'rotation of said first wheel assists in holding the scissors blade against said guide surface, said front wall having means (affording access to the first wheel so that the scissors blade can be sharpened close to the pivotal connection.

*2. In an electrically operated apparatus for sharpening scissors of the type having two shearing blades which are pivotally connected together and knives including a supporting frame, an electrically operated motor mounted on said frame, a first and second abrasive wheel of substantially equal diameter supported by said frame and disposed on spaced parallel axes, said first wheel being posirtioned slightly ahead and to the left of said second wheel and said wheel .axes being sufficiently close so that the wheel peripheries slightly overlap .to define a line of intersection, power transmission means interconnecitng said motor and wheels for rotating said wheels in opposite directions about said axes and said motor rotates in a direction for causing said wheels .to rotate upwardly at said line of intersection, a cup-shaped housing having top, front, rear and end walls which is rigidly associatedwith said frame and enclosing said frame, motor and wheels, said housing defining parallel spaced knife and scissors grooves which extend across said top wall from front to back and are positioned parallel to said axes, said knife groove terminating in an opening positioned Ov the line of intersection and said scissors groove having an opening positioned over said first Wheel which is slightly ofiset from said first wheel axis in a direction remote from said second wheel axis, said soissors groove being formed with a depending guide surfiace extending over said first wheel in order to provide support completely across said first wheel for the scissors blade and the rotation of said first wheel forces the scissors blade against said su'rfiace.

3. In a household knife and scissors sharpener comprising a housing having a top and front Wall which are adapted to receive knives and scissors for sharpening, a first and second cylindrical abrasive wheel disposed on horizontally spaced axes and positioned adjacent said front wall, said first wheel being positionedcloser to said front well then said second wheel and to the left of said second Wheel, said W-heel axes being sufficiently close so that said wheels overlap to define a line of intersection therebetwen, a knife groove formed in the housing top wall extending .through to said front wall and lying over said line of intersection, said knife groove having an opening :at the bottom exposing said wheel-s, a scissors groove spaced to the left of said knife groove in said top wall extending through to said front wall and adapted to References Cited by the Examiner UNITED STATES PATENTS 1,590,619 6/1926 Ernst 51102 2,197,119 4/1940 Barsch 5180 2,617,235 11/ 1952 Lindahl 51-80 2,684,561 7/1954 Lindg'ren 51-102 2,707,852 5/ 1955 FillWe-b'er 51-80 2,768,476 10/ 1956 Jerome et al. 5180 2,865,141 12/1958 Madl et a1. 5180 ROBERT C. RIORDON, Primary Examiner.

LESTER M. SWINGLE, Examiner.

J. A. MATHEWS, Assistant Examiner. 

1. IN AN ELECTRICALLY OPERATED APPARATUS FOR SHARPENING SCISSORS OF THE TYPE HAVING TWO SHEARING BLADES WHICH ARE PIVOTALLY CONNECTED TOGETHER AND KNIVES INCLUDING A FIRST AND SECOND ABRASIVE WHEEL POSITIONED ON PARALLEL HORIZONTAL AXES WHICH ARE LOCATED SUFFICIENTLY CLOSE TOGETHER SO THAT THE PERIPHERIES OF SAID WHEELS OVERLAP SLIGHTLY AND SAID FIRST WHEEL IS SLIGHTLY IN FRONT OF SAID SECOND WHEEL, A HOUSING INCLUDING A TOP WALL SUPERIMPOSED OVER SAID WHEELS AND A FRONT WALL FACING THE SIDE FROM WHICH KNIVES AND SCISSORS ARE PRESENTED FOR SHARPENING, SAID FIRST WHEEL BEING POSITIONED TO THE LEFT OF SAID SECOND WHEEL FROM THE FRONT AND HAVING AN ABRASIVE FACE ON THE PERIPHERY, THE OVERLAPPING OF SAID WHEELS DEFINING AN UPPER LINE OF INTERSECTION, ELECTRICAL MEANS FOR ROTATING SAID WHEELS IN OPPOSITE DIRECTION WHEREBY BOTH WHEELS ROTATE UPWARDLY AT THE LINE OF INTERSECTION, SAID TOP WALL HAVING A KNIFE GROOVE ADAPTED FOR RECEIVING KNIVES TO BE SHARPENED WHICH IS PARALLEL TO AND POSITIONED OVER SAID LIONE OF INTERSECTION AND DEFINGES A KNIFE EXPOSING SAID INTERSECTION, A SCISSORS GROOVE FORMED IN SAID TOP WALL PARALLEL TO AND SPACED TO THE LEFT OF SAID KNIFE GROOVE, SAID SCISSORS GROOVE BEING FORMED IN PART OF A STRAIGHT FLAT GUIDE SURFACE WHICH LIES IN A SUBSTANTIALLY VERTICAL PLANE, SAID SURFACE EXTENDING COMPLETELY ACROSS THE FACE OF SAID FIRST WHEEL AND OFFSET FROM SAID FIRST WHEEL AXIS IN A DIRECTION AWAY FROM SAID SECOND WHEEL AXIS WHEREBY THE ROTATION OF SAID FIRST WHEEL ASSISTS IN HOLDING THE SCISSORS BLADE AGAINST SAID GUIDE SURFACE, SAID FRONT WALL HAVING MEANS AFFORDING ACCESS TO THE FIRST WHEEL SO THAT THE SCISSORS BLADE CAN BE SHARPENED CLOSE TO THE PIVOTAL CONNECTION. 